Effects of cassava waste- and tofu waste-based concentrate formulations on feed intake, nutrient digestibility, growth performance, and economic returns of Madura and Madrasin bulls under smallholder production systems.

Abstract

Background and aim: Feed scarcity and the high cost of commercial concentrates remain major constraints to beef production under Indonesian smallholder systems. Agricultural by-products such as cassava and tofu waste offer potential low-cost alternatives, but information on their combined utilization and breed-specific responses remains limited. This study aimed to evaluate the effects of different cassava waste- and tofu waste-based concentrate formulations on feed intake, nutrient digestibility, growth performance, and economic returns in indigenous Madura and Madrasin (Madura × Limousin) bulls.

Materials and methods: Forty bulls (20 Madura and 20 Madrasin; 2.0-2.5 years old) were used in a 2 × 4 factorial experiment arranged in a randomized complete block design. Four concentrate formulations containing increasing levels of cassava waste (19%-34%) and decreasing levels of tofu waste (20%-5%) were supplied together with native grass. Feed chemical composition was determined, and dry matter intake (DMI), nutrient intake, digestibility coefficients, liveweight gain (LWG), feed conversion ratio (FCR), and income over feed cost (IOFC) were measured. Data were analyzed using mixed-model analysis of variance.

Results: Increasing cassava waste inclusion enhanced DMI, with the highest value observed in Madrasin bulls receiving the T4 diet (7.19 kg/day). Dry matter digestibility ranged from 75.06% to 79.77%, whereas organic matter digestibility ranged from 76.77% to 81.21%. Crude protein digestibility remained relatively stable among treatments. Despite differences in intake and digestibility, LWG (0.62-0.83 kg/day) and FCR (7.58-9.64) were not significantly affected by dietary treatments. Madrasin bulls consistently exhibited greater nutrient intake, superior fiber utilization, higher average daily gain, and greater economic returns than Madura bulls. IOFC reached a maximum of IDR 44,456/day in Madrasin bulls. Importantly, increasing cassava waste from 19% to 34% did not adversely affect growth performance or profitability, indicating that dietary flexibility could be achieved without compromising productive efficiency.

Conclusion: Cassava waste and tofu waste can be effectively combined in concentrate formulations for beef cattle under smallholder conditions. Inclusion of cassava waste up to 34% maintained growth performance, feed efficiency, and profitability while reducing dependence on commercial concentrates. Madrasin bulls exhibited superior productive and economic performance; however, balanced breeding strategies are required to enhance productivity while supporting conservation of the indigenous Madura cattle. These findings provide practical evidence for developing resilient, low-cost, and sustainable feeding systems based on locally available agricultural by-products.